Structurally viscose clear lacquer slurry, method for the production and use thereof

ABSTRACT

A pseudoplastic clearcoat slurry comprising solid and/or highly viscous particles which are dimensionally stable under storage and application conditions and at least one wetting agent selected from the group consisting of alkoxylated fatty alcohols having from 16 to 18 carbon atoms in the alkyl radical and containing on average per molecule at least 20 oxaalkanediyl groups; process for preparing it, and its use.

[0001] The present invention relates to a novel pseudoplastic clearcoatslurry. The present invention also relates to a novel process forpreparing pseudoplastic clearcoat slurries. The present inventionadditionally relates to the use of the novel pseudoplastic clearcoatslurry for automotive OEM finishing, automotive refinish, the interiorand exterior painting of buildings, the coating of doors, windows andfurniture, and industrial coating, including coil coating, containercoating, the coating of small parts, the impregnation and/or coating ofelectrical components, and the coating of white goods. The presentinvention relates not least to the use of the novel clearcoat slurriesas adhesives and sealing compounds for producing adhesive films andseals, especially in the aforementioned fields.

[0002] The German patent application DE 196 17 086 A1 discloses a powderclearcoat slurry preparable by means of a secondary dispersion processin which the dispersing equipment comprises pressure releasehomogenizing nozzles. For stabilizing in addition to the ionicstabilization, it is necessary to employ external emulsifiers or wettingagents as well, but these are not specified in any greater detail.Moreover, these known clearcoat slurries always include certain amountsof organic cosolvents or leveling agents, which cannot be removed asthey are essential for the leveling properties of the initially driedfilm. Prior to the application of the clearcoat slurries, they areadjusted to the application viscosity using thickeners; a complexviscosity behavior, however, is not described.

[0003] A comparable clearcoat slurry is known from the European patentapplication EP 0 899 282 A2. The known clearcoat slurry may be preparedby a direct dispersion process or by the phase inversion process. By thephase inversion process is meant the secondary dispersion process setout below. It is important that preparation is carried out using adispersing apparatus having a volume-related dispersing output of from1×10 to 9.8×10 000 W/cm³. For their stabilization, the known clearcoatslurries require external emulsifiers or wetting agents of which nofurther details are given; a complex viscosity behavior is notdescribed.

[0004] In this situation, the pseudoplastic clearcoat slurry known fromthe German patent DE 198 41 842 C2 provided substantial advances.

[0005] The known pseudoplastic clearcoat slurry is free from organicsolvents and external emulsifiers and comprises solid sphericalparticles with an average size of from 0.8 to 20 μm and a maximum sizeof 30 μm, the clearcoat slurry having an ion-forming group content offrom 0.05 to 1 meq/g, a neutralizing agent content of from 0.05 to 1meq/g, and a viscosity of

[0006] (i) from 50 to 1 000 mPas at a shear rate of 1 000 s⁻¹,

[0007] (ii) from 150 to 8 000 mPas at a shear rate of 10 s⁻¹, and

[0008] (iii) from 180 to 12 000 mPas at a shear rate of 1 s⁻¹.

[0009] The known pseudoplastic clearcoat slurry is prepared by

[0010] 1) emulsifying an organic solution comprising binder andcrosslinking agent in water, to give an emulsion of the oil-in-watertype,

[0011] 2) removing the organic solvent or the organic solvents, and

[0012] 3) replacing by water some or all of the solvent removed, to givea clearcoat slurry comprising solid spherical particles,

[0013] where

[0014] 4) additionally, at least one ionic, especially anionic,thickener and at least one nonionic associative thickener are added tothe clearcoat slurry.

[0015] Here and below, the process in accordance with steps (1) to (3)is referred to as the secondary dispersion process.

[0016] This clearcoat slurry is preparable with a small number ofprocessing steps; on the basis of its typical powder slurry properties,with residual solvent contents of <1%, and its particle sizes, itexhibits advantageous application properties. Even without theassistance of organic solvents, there is generally no popping at therequired film thickness of approximately 40 to 50 μm. Moreover, theparticles of the slurry, owing to mixing of their constituents insolution, are very homogeneous. The resulting clearcoats are bright,chemical-resistant, and flow out very well, without popping marks orcracking.

[0017] The clearcoat slurries are highly suitable for the production ofclearcoats for high-quality multicoat color and/or effect paint systems,such as are used to coat automobiles, for example. In the production ofthese multicoat color and/or effect paint systems, the clearcoatslurries may be used by the wet-on-wet technique in combination with anyof a very wide variety of aqueous basecoat materials, without theoccurrence of deleterious effects such as mudcracking.

[0018] In the German patent application DE 100 01 442.9, unpublished atthe priority date of the present specification, the clearcoat slurry ofthe German patent DE 198 41 842 C2 is subsequently subjected to wetgrinding.

[0019] In the German patent application DE 100 55 464.4, unpublished atthe priority date of the present specification, a pseudoplasticclearcoat slurry free from organic solvents and external emulsifiers isdescribed which comprises solid and/or highly viscous particles whichare dimensionally stable under storage and application conditions,

[0020] 1. said particles

[0021] 1.1 having an average particle size of from 1.0 to 20 μm, atleast 99% of the particles having a size≦30 μm, and

[0022] 1.2 containing as binder at least one polyol with an OHnumber>110 mg KOH/g, containing potentially ionic groups,

[0023] and

[0024] 2. said clearcoat slurry

[0025] 2.1 containing from 0.01 to 1 meq of potentially ionic groups perg of solids,

[0026] 2.2 containing, at a degree of neutralization of not more than50%, an amount of ionic groups produced by neutralization of thepotentially ionic groups of from 0.005 to 0.1 meq/g of solids, and

[0027] 2.3 having a viscosity of (i) from 50 to 1 000 mPas at a shearrate of 1 000 s⁻¹, (ii) from 150 to 8 000 mPas at a shear rate of 10s⁻¹, and (iii) from 180 to 12 000 mPas at a shear rate of 1 s⁻¹.

[0028] The pseudoplastic clearcoat slurries may again be prepared by thesecondary dispersion process.

[0029] The German patent application DE 100 27 290.8, unpublished at thepriority date of the present specification, describes clearcoat slurrieswhich may be prepared, inter alia, by the secondary dispersion process.The essential constituent of the clearcoat slurries is at least oneadduct of ethylene oxide and/or propylene oxide with at least oneglycol, especially ethylene glycol, 1,3- and/or 1,2-propylene glycol or1,2-, 1,3- and/or 1,4-butylene glycol. Examples of highly suitableadducts are polyethylene glycols, polypropylene glycols, blockcopolymers of ethylene oxide and propylene oxide (Pluronics®) orpolytetramethylene glycols (polytetrahydrofurans) (cf. Römpp LexikonLacke und Druckfarben, Georg Thieme Verlag, 1998, page 457,“Polyalkylene glycols”), of which the adducts of propylene oxide with1,3- and/or 1,2-propylene glycol, i.e. the polypropylene glycols, areparticularly advantageous and are therefore used with particularpreference in accordance with the invention. Particularly suitablepolypropylene glycols have a number-average molecular weight of from 350to 1 000, preferably from 400 to 950, with particular preference from450 to 900, with very particular preference from 500 to 850, and inparticular from 550 to 800 daltons. The polypropylene glycols arecommercial products and are sold, for example, by BASFAktiengesellschaft under the brand name Pluriol® 400, 600 and 900, thenumerical suffixes indicating the molecular weight or its order ofmagnitude. The amount of the adducts in the clearcoat slurries ispreferably from 0.01 to 2.0% by weight, based in each case on the solidsof a given clearcoat slurry. The adducts are added to the clearcoatslurries prior to wet grinding.

[0030] Since the clearcoat slurries have to be filtered prior to theirapplication, it is important that they possess good filterability. Inthe plants of the users, especially on the lines of the automobilemanufacturers, they are conveyed through gear pumps. This exposure toload, however, may significantly impair their filterability. Theimpaired filterability of the load-exposed clearcoat slurries results inclearcoats having impaired optical properties (appearance). Addition ofexternal emulsifiers or wetting agents frequently improves thefilterability but impairs the gear-pump conveyability and thepseudo-plasticity of the clearcoat slurries, and also the chemicalresistance of the clearcoats produced from them.

[0031] It is an object of the present invention to provide a novelpseudoplastic clearcoat slurry which no longer has the disadvantages ofthe prior art but which instead combines good filterability with goodgear-pump conveyability. The novel pseudoplastic clearcoat slurry oughtto provide clearcoats which in terms of their optical properties(appearance) and chemical resistance are at least equal to theclearcoats produced from the known clearcoat slurries.

[0032] The invention accordingly provides the novel pseudo-plasticclearcoat slurry comprising solid and/or highly viscous particles whichare dimensionally stable under storage and application conditions and atleast one wetting agent selected from the group consisting ofalkoxylated fatty alcohols having from 16 to 18 carbon atoms in thealkyl radical and containing on average per molecule at least 20oxaalkanediyl groups.

[0033] In the text below, the novel pseudoplastic clearcoat slurry isreferred to as the “slurry of the invention”.

[0034] Further subject matter of the invention will emerge from thedescription.

[0035] In the light of the prior art it was surprising for the skilledworker, and, unforeseeable, that the object on which the presentinvention is based could be achieved by adding small amounts ofspecially selected wetting agents to conventional clearcoat slurries.This was all the more surprising since the prior art bears noindications of any correlation between the wetting agents for use inaccordance with the invention, on the one hand, and the filterabilityand gear-pump conveyability of clearcoat slurries, on the other.

[0036] The slurries of the invention may be of various compositions. Forexample,

[0037] the clearcoat slurries known from the German patent applicationsDE 195 40 977 A1 or DE 19832 2 06 A1, prepared by means of grinding anddispersing processes and curable thermally or with actinic radiation,

[0038] the clearcoat slurries known from the German patent applicationDE 199 59 923 A1, prepared by means of primary dispersion processes andcurable thermally or both thermally and with actinic radiation,

[0039] the clearcoat slurries known from the international patentapplications WO 97/45476, WO 98/45356 or WO 00/17256 or from theAmerican patent U.S. Pat. No. 4,056,653 A, or described in the Germanpatent applications DE 100 06 673.9 or DE 100 18 581.9, both unpublishedat the priority date of the present specification, prepared by means ofmelt emulsification processes and curable thermally or both thermallyand with actinic radiation, or

[0040] the clearcoat slurries known from the German patent applicationsDE 198 41 842 A1, DE 196 17 086 A1 or DE 199 08 018 A1 or from theEuropean patent application EP 0 899 282 A1, or described in the Germanpatent application DE 100 55 464.4, unpublished at the priority date ofthe present specification, prepared by means of secondary dispersionprocesses and curable thermally or both thermally and with actinicradiation

[0041] are a typical basis for the slurries of the invention.

[0042] Of these, the clearcoat slurries known from the German patentapplications DE 198 41 842 A1 or DE 199 08 018 A1 or described in theGerman patent application DE 100 55 464.4, unpublished at the prioritydate of the present specification, prepared by means of secondarydispersion processes and curable thermally or both thermally and withactinic radiation, which are free or substantially free from organicsolvents, are of advantage and are therefore used with preference inaccordance with the invention.

[0043] Very particular preference is given to the clearcoat slurriesprepared by the secondary dispersion process and comprising the specificmethacrylate copolymers described below as binders in the dimensionallystable particles.

[0044] The slurry of the invention comprises as a constituent essentialto the invention at least one, especially one, wetting agent selectedfrom the group consisting of alkoxylated fatty alcohols having from 16to 18 carbon atoms in the alkyl radical and containing on average permolecule at least 20, preferably at least 25, more preferably at least30, with particular preference at least 35, with very particularpreference at least 40, and in particular at least 45, oxaalkane-diylgroups.

[0045] Suitable oxaalkanediyl groups are 1-oxapropane-1,3-diyl,1-oxabutane-1,4-diyl, 1-oxabutane-1,3-diyl, 1-oxapentane-1,5-diyl, and1-oxapentane-1,3-diyl, preferably 1-oxapropane-1,3-diyl and1-oxabutane-1,3-diyl, especially 1-oxapropane-1,3-diyl (ethylene oxidegroup).

[0046] The wetting agent may contain at least two kinds of theseoxaalkanediyl groups. The oxaalkanediyl chains may be random,alternating or blocklike in structure. Preferably, the wetting agentcontains only one kind of oxaalkanediyl groups, in particular theethylene oxide groups.

[0047] The wetting agents used with preference in accordance with theinvention, from the group of the fatty alcohols having from 16 to 18carbon atoms in the alkyl radical and containing at least 20 ethyleneoxide groups in the molecule, are commercially customary compounds andare sold, for example, by BASF Aktiengesellschaft under the brand nameLutensol® AT 25 (25 ethylene oxide groups in the molecule) and AT 50 (50ethylene oxide groups in the molecule).

[0048] The wetting agents for use in accordance with the invention areused preferably in an amount of from 0.01 to 2.5% by weight, morepreferably from 0.05 to 2.4% by weight, with particular preference from0.1 to 2.2% by weight, with very particular preference from 0.15 to 2%by weight, and in particular from 0.2 to 1.8% by weight, based in eachcase on a given clearcoat slurry.

[0049] The slurry of the invention comprises dimensionally stableparticles. In the context of the present invention, “dimensionallystable” means that, under the customary known conditions of storage andapplication of clearcoat slurries, the particles undergo little if anyagglomeration and/or breakdown into smaller particles, but insteadsubstantially retain their original form even under the influence ofshear forces. The particles may be highly viscous and/or solid.Preferably, the dimensionally stable particles are solid.

[0050] For the slurry of the invention it is advantageous if the averagesize of the particles is from 1 to 20 μm and with particular preferencefrom 3 to 15 μm. By average particle size is meant the 50% median valueas determined by the laser diffraction method, i.e., 50% of theparticles have a diameter≦the median value and 50% of the particles havea diameter≧the median value. Preferably, at least 99% of the particleshave a size<30 μm.

[0051] Slurries having average particle sizes of this kind and a solventcontent of<1% exhibit better application properties and, at the appliedfilm thicknesses of>30 μm as presently practiced in the automobileindustry for the finishing of automobiles, exhibit much less of atendency toward popping marks and mudcracking than conventionalclearcoat slurries.

[0052] The upper limit on particle size is reached when the size of theparticles means that they are no longer able to flow out fully onbaking, and thus film leveling is adversely affected. In cases whererequirements regarding the appearance are not very stringent, however,the limit may also be higher. 30 μm is considered a sensible upperlimit, since above this particle size the spray nozzles and the rinsingducts of the highly sensitive application apparatus are likely to becomeblocked.

[0053] The slurry of the invention is, preferably, substantially orentirely free from organic solvents. In the context of the presentinvention this means that it has a residual volatile solvent contentof<3% by weight, preferably<2% by weight, and with particularpreference<1% by weight.

[0054] The slurry of the invention preferably contains from 0.05 to 1,more preferably from 0.05 to 0.9, more preferably still from 0.05 to0.8, with particular preference from 0.05 to 0.7, and in particular from0.05 to 0.6 meq of potentially ionic groups per g of solids. The amountof neutralizing agents is preferably chosen such that the degree ofneutralization is 100%, preferably below 80%, with particular preferencebelow 60%, and in particular below 50%.

[0055] The chemical nature of the binder is generally not restricting inthis respect, provided it contains ion-forming groups which can beconverted into salt groups by neutralization and which, as a result, areable to take over the function of ionic stabilization of the particlesin water.

[0056] Suitable anion-forming groups include acid groups such ascarboxylic acid, sulfonic acid or phosphonic acid groups, especiallycarboxylic acid groups. Accordingly, bases, such as alkali metalhydroxides, ammonia or amines, are used as neutralizing agents. Alkalimetal hydroxides can be used only to a limited extent, since the alkalimetal ions are not volatile on baking and, owing to theirincompatibility with organic substances, may cause the film to becomecloudy and may lead to loss of gloss. Therefore, ammonia or amines arepreferred. In the case of amines, tertiary amines are preferred. By wayof example, mention may be made of N,N-dimethylethanolamine oraminomethylpropanolamine (AMP).

[0057] Suitable cation-forming groups include primary, secondary andtertiary amines. Accordingly, neutralizing agents used are, inparticular, low molecular mass organic acids such as formic acid, aceticacid, dimethylolpropionic acid or lactic acid.

[0058] For the preferred use of the slurry of the invention inautomobile finishing as an unpigmented clearcoat material, preference isgiven to polymers or oligomers containing acid groups as ion-forminggroups, since these so-called anionic binders generally exhibit betterresistance to yellowing than the class of the cationic binders.

[0059] However, cationic binders containing groups which can beconverted into cations, such as amino groups, are likewise suitable foruse in principle, provided the field of use tolerates their typicalsecondary properties such as their tendency toward yellowing.

[0060] Examples of suitable binders are random, alternating and/orblock, linear and/or branched and/or comb, addition (co)polymers ofethylenically unsaturated monomers, or polyaddition resins and/orpoly-condensation resins. For further details of these terms, refer toRömpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart,N.Y., 1998, page 457, “polyaddition” and “polyaddition resins(poly-adducts)”, and also pages 463 and 464, “poly-condensates”,“polycondensation” and “polycondensation resins”, and also pages 73 and74, “binders”.

[0061] Examples of suitable addition (co)polymers are (meth)acrylate(co)polymers or partially saponified polyvinyl esters, especially(meth)acrylate copolymers.

[0062] Examples of suitable polyaddition resins and/or polycondensationresins are polyesters, alkyds, polyurethanes, polylactones,polycarbonates, poly-ethers, epoxy resins, epoxy resin-amine adducts,polyureas, polyamides, polyimides, polyester-polyurethanes,polyether-polyurethanes or polyester-polyether-polyurethanes.

[0063] These oligomers and polymers are known to the skilled worker, andmany suitable compounds are available on the market.

[0064] In accordance with the invention the (meth)acrylate copolymers,the polyesters, the alkyd resins, the polyurethanes and/or the acrylatedpolyurethanes are of advantage and are therefore used with preference.

[0065] Highly suitable (meth)acrylate copolymers and processes forpreparing them are described, for example, in the German patentapplication DE 199 08 018 A1, page 9, line 44, to page 10, line 53, inthe European patent application EP 0 767 185 A1, in the German patentsDE 22 14 650 B1 and DE 27 49 576 B1, and in the American patents U.S.Pat. No. 4,091,048 A, U.S. Pat. No. 3,781,379 A, U.S. Pat. No. 5,480,493A, U.S. Pat. No. 5,475,073 A, and U.S. Pat. No. 5,534,598 A, or in thestandard work by Houben-Weyl, Methoden der organischen Chemie, 4thedition, volume 14/1, pages 24 to 255, 1961. Suitable reactors for thecopolymerization include the customary and known stirred tanks, stirredtank cascades, tube reactors, loop reactors or Taylor reactors, as aredescribed, for example, in the patent applications DE 1 071 241 B1, EP 0498 583 A1 or DE 198 28 742 A1 or in the article by K. Kataoka inChemical Engineering Science, volume 50, No. 9, 1995, pages 1409 to1416.

[0066] Highly suitable polyesters and alkyd resins, and theirpreparation, are described, for example, in the standard work UllmansEncyklopädie der technischen Chemie, 3rd edition, volume 14, Urban &Schwarzenberg, Munich, Berlin, 1963, pages 80 to 89 and pages 99 to 105,and also in the following books: “Résines Alkydes-Polyesters” by J.Bourry, Dunod, Paris, 1952, “Alkyd Resins” by C. R. Martens, ReinholdPublishing Corporation, New York, 1961, and, “Alkyd Resin Technology” byT. C. Patton, Interscience Publishers, 1962.

[0067] Highly suitable polyurethanes and/or acrylated polyurethanes andtheir preparation are described, for example, in the patents EP 0 708788 A1, DE 44 01 544 A1 or DE 195 34 361 A1.

[0068] Very particular advantages result for the slurries of theinvention if their dimensionally stable particles comprise as binder(s)at least one methacrylate copolymer which contains in copolymerizedform, based on a given methacrylate copolymer, at least 90% by weight,preferably at least 95% by weight, and in particular at least 99% byweight of methacrylate comonomers, including methacrylate comonomerscontaining potentially ionic groups.

[0069] Preferably, the (meth)acrylate comonomers containing potentiallyionic groups comprise acrylic acid, beta-carboxyethyl acrylate and/ormethacrylic acid, especially methacrylic acid. The (meth)acrylatecomonomers containing potentially ionic groups are preferablycopolymerized into the methacrylate copolymers in an amount such thatthe above-described amount of potentially ionic groups in the particlescan be set without problems. They are copolymerized into themethacrylate copolymers preferably in an amount of from 0.1 to 3%, morepreferably from 0.2 to 2.8%, with particular preference from 0.3 to2.6%, with very particular preference from 0.4 to 2.4%, and inparticular from 0.5 to 2.2% by weight, based in each case on a givenmethacrylate copolymer.

[0070] The methacrylate copolymers preferably have a glass transitiontemperature, Tg, of not more than 50° C.; at the same time the glasstransition temperature Tg should not go below preferably 0° C., morepreferably 10° C., and in particular 20° C.

[0071] The glass transition temperature, Tg, of the methacrylatecopolymers is preferably set by way of at least one methacrylatecomonomer which is free from reactive functional groups and frompotentially ionic groups. More preferably, the glass transitiontemperature, Tg, is set by way of at least two, in particular two,methacrylate comonomers which are free from reactive functional groupsand from potentially ionic groups. Preferably, the glass transitiontemperatures, Tg, of the respective homopolymers of the methacrylatecomonomers that are free from reactive functional groups and frompotentially ionic groups differ from one another by not more than 40° C.

[0072] Examples of suitable methacrylate comonomers free from reactivefunctional groups and from potentially ionic groups are methyl, ethyl,n-propyl, n-butyl, i-butyl, tert-butyl, n-pentyl, isoamyl, cyclopentyl,n-hexyl and cyclohexyl methacrylate. Of these, i-butyl methacrylate(glass transition temperature, Tg, of the homopolymer: 53° C.) andn-butyl methacrylate (glass transition temperature, Tg, of thehomopolymer: 20° C.) are of advantage and are therefore used withparticular preference.

[0073] The amount of the copolymerized methacrylate comonomers, freefrom reactive functional groups and from potentially ionic groups, thatis copolymerized into the methacrylate copolymers for use in accordancewith the invention may vary widely. It is essential that the amount ischosen such that the resulting methacrylate copolymers have the glasstransition temperature, Tg, described above. The amount is preferably atleast 50%, more preferably at least 55%, with particular preference atleast 60%, with very particular preference at least 65%, and inparticular at least 70% by weight, based in each case on a givenmethacrylate copolymer.

[0074] The weight ratio of the methacrylate comonomers used withparticular preference, n-butyl methacrylate and i-butyl methacrylate,may vary widely. The n:i weight ratio is preferably from 10:1 to 1:6,more preferably from 8:1 to 1:4, with particular preference from 6:1 to1:2, with very particular preference from 5:1 to 1:1.5, and inparticular from 4:1 to 1:1.

[0075] Where the slurries of the invention are physically curableslurries, the methacrylate copolymers contain reactive functionalgroups, if at all, only in a number which is insubstantial as far ascrosslinking is concerned.

[0076] Where the slurries of the invention are thermallyself-crosslinking, the methacrylate copolymers contain the complementaryreactive functional groups for thermal crosslinking, described below,and/or reactive functional groups which are able to crosslink “withthemselves”, i.e., with groups of their own kind.

[0077] Where the slurries of the invention are curable with actinicradiation, the methacrylate copolymers may contain reactive functionalgroups having at least one bond which can be activated with actinicradiation. These reactive functional groups are mandatorily present inthe methacrylate copolymers of the slurries of the invention that arecurable with actinic radiation if the slurries contain no otherradiation-curable constituents.

[0078] Where the slurries of the invention are dual-cure slurries, themethacrylate copolymers contain reactive functional groups for thermalcrosslinking and/or reactive functional groups containing at least onebond which can be activated with actinic radiation. The reactivefunctional groups containing at least one bond which can be activatedwith actinic radiation are mandatorily present in the methacrylatecopolymers of the dual-cure slurries of the invention if the dual-cureslurries contain no other radiation-curable constituents.

[0079] Examples of suitable complementary reactive functional groups foruse in accordance with the invention are placed together in thefollowing overview. In the overview, the variable R stands for anacyclic or cyclic aliphatic radical, an aromatic radical and/or anaromatic-aliphatic (araliphatic) radical; the variables R′ and R″ standfor identical or different aliphatic radicals or are linked with oneanother to form an aliphatic or heteroaliphatic ring. Overview:Examplesof complementary reactive functional groups Binder and crosslinkingagent or Crosslinking agent and binder —SH —C(O)—OH —NH₂ —C(O)—O—C(O)——OH —NCO —O—(CO)—NH—(CO)—NH₂ —NH—C(O)—OR —O—(CO)—NH₂ —CH₂—OH >NH—CH₂—O—R —NH—CH₂—O—R —NH—CH₂—OH —N(—CH₂—O—R)₂ —NH—C(O)—CH(—C(O)OR)₂—NH—C(O)—CH(—C(O)OR)(—C(O)—R) —NH—C(O)—NR′R″ >Si(OR)₂

—C(O)—OH

—C(O)—N(CH₂—CH₂—OH)₂

[0080] The selection of the respective complementary reactive functionalgroups is guided on the one hand by the consideration that they shouldnot enter into any unwanted reactions during the preparation of thebinders and during the preparation, storage, application, and melting ofthe slurries of the invention, and in particular should not form anypolyelectrolyte complexes or undergo premature cross-linking, and/ormust not disrupt or inhibit curing with actinic radiation, and secondlyby the temperature range within which crosslinking is to take place.

[0081] For the slurries of the invention it is preferred to employcrosslinking temperatures of from 60 to 180° C. Use is therefore madepreferably of binders containing thio, hydroxyl, N-methylolamino,N-alkoxymethylamino, imino, carbamate, and/or allophanate groups,preferably hydroxyl groups, on the one hand and, preferably,crosslinking agents containing anhydride, epoxy, blocked and unblocked,especially blocked, isocyanate, urethane, methylol, methylol ether,siloxane, carbonate, amino, hydroxyl and/or beta-hydroxyalkylamidegroups, preferably blocked isocyanate, carbamate and/orN-alkoxymethylamino groups, on the other.

[0082] In the case of self-crosslinking slurries of the invention, thebinders contain, in particular, methylol, methylol ether and/orN-alkoxymethylamino groups.

[0083] Complementary reactive functional groups which are especiallysuitable for use in the thermally externally crosslinking slurries ofthe invention and the dual-cure slurries of the invention are hydroxylgroups on the one hand and blocked isocyanate groups on the other.

[0084] The functionality of the binders in respect of the reactivefunctional groups described above may vary very widely and is guided inparticular by the desired crosslinking density and/or by thefunctionality of the crosslinking agents that are employed in each case.In the case of hydroxyl-containing binders, for example, the OH numberis preferably from 20 to 300, more preferably from 40 to 250, withparticular preference from 60 to 200, with very particular preferencefrom 80 to 190, and in particular from 90 to 180 mg KOH/g.

[0085] The above-described complementary reactive functional groups maybe incorporated into the binders in accordance with the customary andknown methods of polymer chemistry. This can be done, for example,through the incorporation of methacrylate comonomers which carry thecorresponding reactive functional groups, and/or with the aid ofpolymer-analogous reactions.

[0086] Examples of suitable methacrylate comonomers containing reactivefunctional groups are methacrylate comonomers which carry at least onehydroxyl, amino, alkoxymethyl-amino, carbamate, allophanate or iminogroup per molecule, such as

[0087] hydroxyalkyl esters of methacrylic acid, which are derived froman alkylene glycol which is esterified with the acid, or which areobtainable by reaction of the methacrylic acid with an alkylene oxidesuch as ethylene oxide or propylene oxide, especially hydroxyalkylesters of methacrylic acid in which the hydroxyalkyl group contains upto 20 carbon atoms, such as 2-hydroxy-ethyl, 2-hydroxypropyl,3-hydroxypropyl, 3-hydroxybutyl or 4-hydroxybutyl methacrylate; orhydroxycycloalkyl esters such as 1,4-bis(hydroxy-methyl)cyclohexane,octahydro-4,7-methano-1H-indenedimethanol or methylpropanediolmonometh-acrylate; or reaction products of cyclic esters, such asepsilon-caprolactone, and these hydroxy-alkyl methacrylates;

[0088] reaction products of methacrylic acid of the glycidyl ester of analpha-branched monocarboxylic acid having from 5 to 18 carbon atoms permolecule, particularly a Versatic® acid, or instead of the reactionproduct an equivalent amount of methacrylic acid, which is then reacted,during or after the polymerization reaction, with the glycidyl ester ofan alpha-branched monocarboxylic acid having from 5 to 18 carbon atomsper molecule, particularly a Versatic® acid;

[0089] aminoethyl methacrylate or N-methylaminoethyl methacrylate, whichmay also be used to introduce potentially ionic groups;

[0090] N,N-di(methoxymethyl)aminoethyl methacrylate orN,N-di(butoxymethyl)aminopropyl methacrylate;

[0091] methacrylamides such as methacrylamide, N-methyl-, N-methylol-,N,N-dimethylol-, N-methoxymethyl-, N,N-di(methoxymethyl)-,N-ethoxymethyl- and/or N,N-di(ethoxyethyl)-methacrylamide;

[0092] methacryloyloxyethyl, -propyl or -butyl carbamate or allophanate;further examples of suitable methacrylate comonomers containingcarbamate groups are described in the patents U.S. Pat. No. 3,479,328 A,U.S. Pat. No. 3,674,838 A, U.S. Pat. No. 4,126,747 A, U.S. Pat. No.4,279,833 A or U.S. Pat. No. 4,340,497 A.

[0093] In minor amounts, the reactive functional groups for thermalcrosslinking may be introduced by way of other olefinically unsaturatedmonomers, such as the corresponding acrylates, allylamine, allyl alcoholor polyols, such as trimethylolpropane monoallyl or diallyl ether orpentaerythritol monoallyl, diallyl or triallyl ether.

[0094] The binders of the dual-cure slurries may contain on average permolecule at least one, preferably at least two, group(s) containing atleast one bond which can be activated with actinic radiation.

[0095] In the context of the present invention, a bond which can beactivated with actinic radiation means a bond which, on exposure toactinic radiation, becomes reactive and, together with other activatedbonds of its kind, enters into polymerization reactions and/orcrosslinking reactions which proceed in accordance with free-radicaland/or ionic mechanisms. Examples of suitable bonds are carbon-hydrogensingle bonds or carbon-carbon, carbon-oxygen, carbon-nitrogen,carbon-phosphorus or carbon-silicon single bonds or double bonds. Ofthese, the carbon-carbon double bonds are particularly advantageous andare therefore used with very particular preference in accordance withthe invention. For the sake of brevity, they are referred to below as“double bonds”.

[0096] Accordingly, the group that is preferred in accordance with theinvention contains one double bond or two, three or four double bonds.Where more than one double bond is used, the double bonds may beconjugated. In accordance with the invention, however, it is ofadvantage if the double bonds are present in isolation, in particulareach terminally, within the group in question. It is of particularadvantage in accordance with the invention to use two double bonds,especially one double bond.

[0097] The dual-cure binder contains on average at least one of theabove-described groups which can be activated with actinic radiation.This means that the functionality of the binder in this respect isintegral, i.e., for example, is two, three, four, five or more, or isnonintegral, i.e., for example, is from 2.1 to 10.5 or more. Thedecision as to which functionality is chosen is guided by therequirements which are imposed on the respective dual-cure slurries.

[0098] Where on average per molecule more than one group which can beactivated with actinic radiation is used, the groups are structurallydifferent from one another or of the same structure.

[0099] Where they are structurally different from one another, thismeans in the context of the present invention that two, three, four ormore, but especially two, groups which can be activated with actinicradiation are used which derive from two, three, four or more, butespecially two, monomer classes.

[0100] Examples of suitable groups are (meth)acrylate, ethacrylate,crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl,norbornenyl, isoprenyl, isopropenyl, allyl or butenyl groups;dicyclo-pentadienyl ether, norbornenyl ether, isoprenyl ether,isopropenyl ether, allyl ether or butenyl ether groups;dicyclopentadienyl ester, norbornenyl ester, isoprenyl ester,isopropenyl ester, allyl ester or butenyl ester groups, but especiallyacrylate groups.

[0101] The groups are attached to the respective parent structures ofthe binders preferably by way of urethane, urea, allophanate, ester,ether and/or amide groups, but in particular by way of ester groups.This is normally done by means of customary and known continuouspolymer-analogous reactions such as, for instance, the reaction ofpendant glycidyl groups with olefinically unsaturated comonomerscontaining an acid group, of pendant hydroxyl groups with the halides ofthese comonomers, of hydroxyl groups with isocyanates containing doublebonds, such as vinyl isocyanate, methacryloyl isocyanate and/or1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (TMI® fromCYTEC), or of pendant isocyanate groups with the hydroxyl-containingcomonomers described above.

[0102] In the particles it is, however, also possible to employ mixturesof binders that are curable by means of heat alone and of binders thatare curable by means of actinic radiation alone.

[0103] Processes for preparing the methacrylate copolymers used withpreference are known from the patent applications, patents andliterature references cited above. With particular preference, themethacrylate copolymers are prepared under pressure.

[0104] The amount of the binders described above in the dimensionallystable particles may vary widely. In the case of the thermallyexternally crosslinking or of the thermally externally crosslinking andactinic-radiation-curable slurries of the invention said amount ispreferably from 5 to 80%, more preferably from 6 to 75%, with particularpreference from 7 to 70%, with very particular preference from 8 to 65%and in particular from 9 to 60% by weight, based in each case on thesolids of the slurries of the invention. In the case of the slurries ofthe invention that are curable physically and those that are curablewith actinic radiation, but especially those that are curablephysically, the amount may be up to 100% by weight.

[0105] The dimensionally stable particles of the slurries of theinvention that are curable thermally, or thermally and with actinicradiation, may comprise crosslinking agents which contain complementaryreactive functional groups for thermal crosslinking and/or reactivefunctional groups containing at least one bond which can be activatedwith actinic radiation.

[0106] Suitable crosslinking agents are all crosslinking agents that arecustomary in the field of light-stable clearcoats. Examples of suitablecrosslinking agents are

[0107] amino resins, as described for example in Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, 1998, page 29, “amino resins”, in thetextbook “Lackadditive” [Additives for coatings] by Johan Bieleman,Wiley-VCH, Weinheim, N.Y., 1998, pages 242 ff., in the book “Paints,Coatings and Solvents”, second, completely revised edition, edited by D.Stoye and W. Freitag, Wiley-VCH, Weinheim, N.Y., 1998, pages 80 ff., inthe patents U.S. Pat. No. 4,710,542 A1 or EP 0 245 700 A1, and in thearticle by B. Singh and coworkers, “Carbamylmethylated Melamines, NovelCrosslinkers for the Coatings Industry”, in Advanced Organic CoatingsScience and Technology Series, 1991, volume 13, pages 193 to 207;

[0108] carboxyl-containing compounds or resins, as described for examplein the patent DE 196 52 813 A1 or 198 41 408 A1, especially 1,12-dodecanedioic acid,

[0109] resins or compounds containing epoxide groups, as described forexample in the patents EP 0 299 420 A1, DE 22 14 650 B1, DE 27 49 576B1, U.S. Pat. No. 4,091,048 A or U.S. Pat. No. 3,781,379 A;

[0110] tris(alkoxycarbonylamino)triazines, as described in the patentsU.S. Pat. No. 4,939,213 A, U.S. Pat. No. 5,084,541 A, U.S. Pat. No.5,288,865 A or in the patent application EP 0 604 922 A;

[0111] blocked polyisocyanates, as described for example in the patentsU.S. Pat. No. 4,444,954 A1, DE 196 17 086 A1, DE 196 31 269 A1, EP 0 004571 A1 or EP 0 582 051 A1; or

[0112] beta-hydroxyalkylamides such asN,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide orN,N,N′,N′-tetrakis(2-hydroxypropyl)adipamide.

[0113] The crosslinking agents described above may be used individuallyor as a mixture of at least two crosslinking agents. In accordance withthe invention, the blocked polyisocyanates and/ortris(alkoxy-carbonylamino)triazines, especially the blockedpoly-isocyanates, afford particular advantages and are therefore usedwith particular preference.

[0114] The amount of crosslinking agent(s) in the dimensionally stableparticles of the slurry of the invention may likewise vary widely and isguided primarily by the functionality and amount of the binders on theone hand and by the functionality of the crosslinking agents on theother. The amount is preferably from 10 to 95%, more preferably from 12to 94%, with particular preference from 14 to 93%, with very particularpreference from 16 to 92%, and in particular from 18 to 90% by weight,based in each case on the solids of the slurry of the invention.

[0115] In addition to the essential constituents described above, thedimensionally stable particles of the slurry of the invention maycomprise additives such as are commonly used in clearcoat materials. Itis essential that these additives do not substantially lower the glasstransition temperature, Tg, of the binders.

[0116] Examples of suitable additives are polymers (other than theabove-described binders and crosslinking agents), crosslinkingcatalysts, defoamers, adhesion promoters, additives for improvingsubstrate wetting, additives for improving surface smoothness, flattingagents, light stabilizers, corrosion inhibitors, biocides, flameretardants, and polymerization inhibitors, especially photoinhibitors,as described in the book “Lackadditive” by Johan Bieleman, Wiley-VCH,Weinheim, N.Y., 1998.

[0117] Moreover, the dimensionally stable particles may also compriseconstituents curable with actinic radiation, different than the bindersdescribed above, as additives if the slurry of the invention is to becurable thermally and with actinic radiation or with actinic radiationalone. Examples of such constituents include

[0118] the binders envisaged for use in UV-curable clearcoat materialsand powder clearcoat materials and described in the European patentapplications EP 0 928 800 A1, EP 0 636 669 A1, EP 0 410 242 A1, EP 0 783534 A1, EP 0 650 978 A1, EP 0 650 979 A1, EP 0 650 985 A1, EP 0 540 884A1, EP 0 568 967 A1, EP 0 054 505 A1 or EP 0 002 866 A1, the Germanpatent applications DE 197 09 467 A1, DE 42 03 278 A1, DE 33 16 593 A1,DE 38 36 370 A1, DE 24 36 186 A1 or DE 20 03 579 B1, the internationalpatent applications WO 97/46549 or WO 99/14254 or the American patentsU.S. Pat. No. 5,824,373 A, U.S. Pat. No. 4,675,234 A, U.S. Pat. No.4,634,602 A, U.S. Pat. No. 4,424,252 A, U.S. Pat. No. 4,208,313 A, U.S.Pat. No. 4,163,810 A, U.S. Pat. No. 4,129,488 A, U.S. Pat. No. 4,064,161A or U.S. Pat. No. 3,974,303 A;

[0119] reactive diluents curable with actinic radiation, such as thosedescribed in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,Stuttgart, N.Y., 1998, on page 491 under the headword “reactivediluents”; or

[0120] photoinitiators as described in Römpp Chemie Lexikon, 9th,expanded and revised edition, Georg Thieme Verlag, Stuttgart, vol. 4,1991, or in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,Stuttgart, 1998, pages 444 to 446.

[0121] The slurry of the invention may likewise comprise additives inthe aqueous phase.

[0122] Preferably, the additives in question are nonionic and/or ionicthickeners. This effectively counters the tendency of the comparativelylarge solid particles toward sedimentation.

[0123] Examples of nonionic thickeners are hydroxyethyl-cellulose andpolyvinyl alcohols. So-called nonionic associative thickeners arelikewise available on the market in a diverse selection. They generallycomprise water-dilutable polyurethanes which are reaction products ofwater-soluble polyetherdiols, aliphatic diisocyanates, andmonofunctional hydroxyl compounds with an organophilic radical.

[0124] Likewise available commercially are ionic thickeners. Thesenormally contain anionic groups and are based in particular on specialpolyacrylate resins with acid groups, some or all of which may have beenneutralized.

[0125] Examples of suitable thickeners for use in accordance with theinvention are known from the text book “Lackadditive” by Johan Bieleman,Wiley-VCH, Weinheim, N.Y., 1998, pages 31 to 65, or from the Germanpatent application DE 199 08 018 A1, page 13, line 18 to page 14, line48.

[0126] For the slurry of the invention it may be advantageous if both ofthe above-described types of thickener are present therein. In by farthe majority of cases, however, one thickener is sufficient,particularly a nonionic thickener, to provide the desiredpseudo-plasticity.

[0127] The amount of thickeners to be added, and, where two differentthickeners are employed, the ratio of ionic to nonionic thickener, areguided by the desired viscosity of the slurry of the invention, which inturn is determined by the required sedimentation stability and thespecific requirements of spray application. The skilled worker istherefore able to determine the amount of the thickeners and, whereappropriate, the ratio of the thickener types to one another on thebasis of simple considerations, possibly with the aid of preliminarytests.

[0128] The viscosity is preferably set to within a range from 50 to 1500 mPas at a shear rate of 1 000 s⁻¹ and from 150 to 8 000 mPas at ashear rate of 10 s⁻¹, and also from 180 to 12 000 mPas at a shear rateof 1 s⁻¹.

[0129] This viscosity behavior, known as “pseudoplasticity”, describes astate which does justice both to the requirements of spray application,on the one hand, and to the requirements in terms of storage andsedimentation stability, on the other: in the state of motion, such aswhen pumping the slurry of the invention in circulation in the ringcircuit of the coating plant and when spraying, for example, the slurryof the invention adopts a state of low viscosity which ensures easyprocessability. In the absence of shear stress, on the other hand, theviscosity rises and thus ensures that the coating material alreadypresent on the substrate to be coated has a reduced tendency to formruns on vertical surfaces. In the same way, a result of the higherviscosity in the stationary state, such as during storage, for instance,is that sedimentation of the solid particles is very largely preventedor that any slight degree of settling of the slurry of the inventionduring the storage period can be removed again by agitation.

[0130] The aqueous phase of the slurry of the invention may furthercomprise leveling assistants which can be incorporated in the film bycrosslinking. Examples of suitable constituents of this kind arethermally curable reactive diluents such as positionally isomericdiethyloctanediols or hydroxyl-containing hyperbranched compounds ordendrimers such as are described in the German patent applications DE198 05 421 A1, DE 198 09 643 A1 or DE 198 40 405 A1.

[0131] In its aqueous phase the slurry of the invention may furthercomprise at least one, especially one, water-soluble salt, preferably inan amount of from 0.1 to 50 mmol per 1 000 g of water in the slurry ofthe invention. The salt is decomposable without residue or substantiallywithout residue. This means that its decomposition is not accompanied bythe formation of any residues at all, or is accompanied only by theformation of residues in an amount which induces no deleterioustechnical effects in the clearcoats of the invention.

[0132] The salt may be decomposable by means of heat and/or actinicradiation. Preferably, it is thermally decomposable. It is preferablydecomposable under the conditions of the curing of the clearcoat filmsof the invention produced from the slurries of the invention. It is ofadvantage in accordance with the invention if the salt is decomposableat temperatures above 100° C. The decomposition of the salt ispreferably at an end at 250° C., more preferably 200° C., withparticular preference 190° C., and in particular 180° C.

[0133] The decomposition of the salt may be accompanied by formation ofany of a very wide variety of organic, inorganic and organometallicdecomposition products. The decomposition products, accordingly, maycomprise volatile elements, neutral organic or inorganic hydrogencompounds, organic and inorganic bases, organic and inorganic acids, oroxides.

[0134] Examples of volatile elements are phosphorus, sulfur, nitrogenand oxygen, especially nitrogen.

[0135] Examples of neutral organic and inorganic hydrogen compounds arewater and hydrocarbons, especially water.

[0136] Examples of organic and inorganic bases are ammonia, methylamine,dimethylamine and trimethylamine, especially ammonia.

[0137] Examples of organic and inorganic acids are formic acid, aceticacid, propionic acid, oxalic acid, citric acid, tartaric acid,hydrochloric acid, hydrogen bromide, phosphoric acid, phosphorous acid,amidosulfonic acid, sulfuric acid, sulfurous acid, thiosulfuric acid,HSCN and hydrogen sulfide, especially acetic acid.

[0138] Examples of oxides are carbon dioxide, sulfur dioxide, sulfurtrioxide and phosphorus oxide, especially carbon dioxide.

[0139] It is preferred to select a salt whose decomposition products areof little or no toxicity and/or of little or no corrosiveness.Preference is given to selecting a salt which forms, as itsdecomposition products, water, nitrogen, carbon dioxide, ammonia andorganic acids.

[0140] With particular preference, the salt is selected from the groupof ammonium salts, with very particular preference from the groupconsisting of salts of ammonia and of organic amines with organic andinorganic acids.

[0141] The ammonium salt is selected in particular from the groupconsisting of ammonium carbonate, ammonium thiocyanate, ammoniumsulfamate, ammonium sulfite monohydrate, ammonium formate, ammoniumacetate, ammonium hydrogen oxalate monohydrate, diammonium oxalatemonohydrate, ammonium citrate, and ammonium tartrate. Of these, in turn,ammonium carbonate and ammonium acetate are very particularlyadvantageous and are therefore used with very particular preference inaccordance with the invention.

[0142] The slurry of the invention is preferably prepared by thesecondary dispersion processes from the German patent application DE 19908 018 A1 or from the German patent DE 198 41 842 C2 or described in theGerman patent application 100 55 464.4, unpublished at the priority dateof the present specification.

[0143] For this process, the ionically stabilizable binders and thecrosslinking agents and also, where appropriate, the additives are mixedin organic solution and dispersed together in water with the aid ofneutralizing agents. The dispersion is then diluted with water, whilestirring. To start with a water-in-oil emulsion is formed, which onfurther dilution is transformed into an oil-in-water emulsion. Thispoint is generally reached at solids contents of<50% by weight, based onthe emulsion, and is evident externally from a relatively sharp fall inviscosity in the course of the dilution.

[0144] The oil-in-water emulsion may also be prepared directly by themelt emulsification of the binders and of the crosslinking agents andalso, where appropriate, of the additives in water.

[0145] It is of advantage in accordance with the invention if thewetting agents for use in accordance with the invention are added to theorganic solution and/or to the water before or during emulsification.They are preferably added to the organic solution.

[0146] The resulting emulsion, which still contains solvents, issubsequently freed from its solvents by azeotropic distillation.

[0147] In accordance with the invention it is of advantage if thesolvents to be removed are distilled off at a distillation temperaturebelow 70° C., preferably below 50° C., and in particular below 40° C. Ifdesired, the distillation pressure is chosen so that this temperaturerange is observed in the case of relatively higher-boiling solvents.

[0148] At its most simple, the azeotropic distillation may be effectedby stirring the emulsion at room temperature in an open vessel forseveral days. Preferably, the solvent-containing emulsion is freed fromits solvents by vacuum distillation.

[0149] In order to avoid high viscosities, the amount of water andsolvents removed by evaporation or distillation is replaced by water.The water may be added before, during, or after the evaporation ordistillation, by addition in portions.

[0150] Following the loss of solvents, the glass transition temperature,Tg, of the dispersed particles rises and a dispersion, i.e. the slurryof the invention, forms instead of the previous solvent-containingemulsion.

[0151] The salts for use in accordance with the invention may beintroduced into the slurries of the invention, or their precursors, in avariety of ways. For example, the salts may be added to customary andknown clearcoat slurries to give the slurries of the invention. They mayalso be added to the organic solution of constituents of the powderslurry of the invention. Preferably, they are dissolved in the waterprior to the emulsification of the organic solution.

[0152] If desired, the particles of the slurry of the invention aremechanically comminuted in the wet state, a procedure also referred toas wet grinding. In the course of this treatment it is preferred toemploy conditions such that the temperature of the material being grounddoes not exceed 70° C., more preferably 60° C., and in particular 50° C.The specific energy input during the grinding process is preferably from10 to 1 000, more preferably from 15 to 750, and in particular from 20to 500 Wh/g.

[0153] For wet grinding it is possible to employ a very wide variety ofequipment which produces high or low shear fields.

[0154] Examples of suitable equipment producing low shear fields arecustomary and known stirred tanks, slot homogenizers, microfluidizers,and dissolvers.

[0155] Examples of suitable equipment producing high shear fields arecustomary and known stirred mills and inline dissolvers.

[0156] Particular preference is given to employing the equipment whichproduces high shear fields. Of this equipment, the stirred mills areparticularly advantageous in accordance with the invention and aretherefore used with very particular preference.

[0157] During wet grinding, generally, the slurry of the invention issupplied to the above-described equipment, and circulated therein, bymeans of appropriate devices, such as pumps, in particular gear pumps,until the desired particle size has been reached.

[0158] The slurry of the invention advantageously has a solids contentof from 10 to 60% by weight, in particular from 20 to 50% by weight.

[0159] The slurry of the invention is preferably filtered prior to itsuse. This is done using the customary and known filtration equipment andfilters, such as are also suitable for filtering the known clearcoatslurries. The mesh size of the filters may vary widely and is guidedprimarily by the size and size distribution of the particles of theslurry of the invention. The skilled worker is therefore easily able todetermine the appropriate filters on the basis of this physicalparameter. Examples of suitable filters are monofilament flat filters orbag filters. These are available on the market under the brand namesPong® or Cuno®. It is preferred to use bag filters having mesh sizes offrom 25 to 50 μm, examples being Pong® 25 to Pong® 50.

[0160] To produce the clearcoats of the invention, the slurry of theinvention is applied to the substrate that is to be coated. No specialmeasures need be taken here; instead, the application may take place inaccordance with the customary and known processes, which is anotherparticular advantage of the slurry of the invention.

[0161] Following its application, the slurry of the invention drieswithout problems and does not film at the processing temperature,generally at room temperature. In other words, the slurry of theinvention, applied as a wet film, loses water when flashed off at roomtemperature or slightly elevated temperatures, with the particlespresent therein changing their original form. As a result, the tendencytoward mudcracking is extremely low.

[0162] In the subsequent baking step, the now substantially water-freepowder layer is caused to crosslink. In some cases it may be ofadvantage to carry out the leveling process and the crosslinkingreaction with a chronological offset, by operating a staged heatingprogram or a so-called heating ramp. The crosslinking temperature thatis appropriate for the present examples is situated between 120 and 160°C. The corresponding baking time is between 20 and 60 minutes.

[0163] In the case of the dual-cure slurry of the invention, thermalcuring is supplemented by curing with actinic radiation, which may becarried out using the customary and known radiation sources andprocesses, such as are described, for example, in the German patentapplication DE 198 18 735 A1, column 10, line 31 to column 11, line 22.These processes and equipment may also be used to cure the slurry of theinvention that is curable with actinic radiation.

[0164] The resultant clearcoat has outstanding performance properties.For instance, it adheres firmly to all customary and known basecoats orto substrates such as metal, glass, wood, ceramic, stone, concrete orplastic. It is of high gloss, smooth, scratch-resistant, stable toweathering and chemicals, and even at high coat thicknesses is free fromdefects, such as stress cracks or popping marks. It no longer exhibitsany blushing on exposure to moisture. Furthermore, it is free frommicrodefects and displays no disruptive optical effects, such as astarry sky that is similar to the metallic effect.

[0165] Above all, however, the slurry of the invention possesses verygood filterability in combination with very good gear pumpconveyability.

[0166] On the basis of this advantageous profile of properties, theslurry of the invention is outstandingly suitable for automotive OEMfinishing, automotive refinish, the interior and exterior painting ofbuildings, the coating of doors, windows and furniture, and industrialcoating, including coil coating, container coating, the coating of smallparts, the impregnation and/or coating of electrical components, or thecoating of white goods. It is used in particular to produce clearcoatsas part of multicoat color and/or effect paint systems, which areproduced from basecoat materials and the slurry of the invention by thecustomary and known wet-on-wet techniques.

[0167] For the wet-on-wet technique, the slurry of the invention mayreadily be combined with numerous basecoat materials, especially aqueousbasecoat materials, without the occurrence of problems, such ascracking, lack of wettability, or poor intercoat adhesion.

[0168] The slurry of the invention may surprisingly also be used as anadhesive for producing adhesive films and as a sealing compound forproducing seals, especially in the technical fields referred to above.

INVENTIVE AND COMPARATIVE EXAMPLES Preparation Example 1

[0169] The preparation of a methacrylate copolymer (binder) forinventive use

[0170] 39.75 parts by weight of methyl ethyl ketone were charged to areaction vessel equipped with stirrer, reflux condenser, oil heating,nitrogen inlet pipe and two feed vessels, and this initial charge washeated to 78° C.

[0171] Thereafter, an initiator solution of 4 parts by weight of methylethyl ketone and 5 parts by weight of TBPEH was metered in at a uniformrate from the first feed vessel over the course of 6.75 h.

[0172] Fifteen minutes after the beginning of the initiator feed, amonomer mixture of 27.5 parts by weight of n-butyl methacrylate, 9.15parts by weight of i-butyl methacrylate, 12.75 parts by weight ofhydroxyethyl methacrylate and 0.6 part by weight of methacrylic acid wasmetered in at a uniform rate from the second feed vessel over the courseof 6 h. The monomer line was then flushed with 0.25 part by weight ofmethyl ethyl ketone and the feed vessel with 0.5 part by weight ofmethyl ethyl ketone. After the end of the initiator feed, the feedvessel in question was likewise flushed with 0.5 part by weight ofmethyl ethyl ketone.

[0173] The reaction mixture was left to react at 78° C. for a further 3h. The volatile fractions were then removed by vacuum distillation untilthe solids content was 70% by weight. The resin solution was thendischarged. It had a viscosity of from 7.0 to 10.0 dPas (resin solids,60 percent, xylene, at 23° C.). The acid number was from 9.0 to 11.0 andthe hydroxyl number was 110 mg KOH/g resin solids.

Preparation Example 2

[0174] The preparation of a blocked polyisocyanate based onhexamethylene diisocyanate

[0175] 534 parts by weight of Desmodur® N 3300 (commercial isocyanurateof hexamethylene diisocyanate from Bayer AG) and 200 parts by weight ofmethyl ethyl ketone were charged to a reaction vessel and this initialcharge was heated to 40° C. 100 parts by weight of 2,5-dimethylpyrazolewere added to the solution, with cooling, and the subsidence of theexothermic reaction was awaited. Thereafter, with continued cooling, afurther 100 parts by weight of 2,5-dimethylpyrazole were added. Afterthe exothermic reaction had again subsided, a further 66 parts by weightof 2,5-dimethyl-pyrazole were added. Cooling was then switched off, as aresult of which the reaction mixture slowly warmed up to 80° C. It washeld at this temperature until its isocyanate content had fallen tobelow 0.1%. The reaction mixture was then cooled and discharged.

[0176] The resulting solution of the blocked polyisocyanate had a solidscontent of 81% by weight (1 h at 130° C.) and a viscosity of 3.4 dPas(70% in methyl ethyl ketone; cone and plate viscometer at 23° C.).

Inventive Examples 1 to 4 and Comparative Examples C1 and C2

[0177] The preparation of inventive slurries (examples 1 to 4) andnoninventive slurries (examples C1 and C2), and their performanceproperties

Example 1

[0178]961.8 parts by weight of the methacrylate copolymer solution frompreparation example 1 and 484.6 parts by weight of the solution of theblocked polyisocyanate from preparation example 2 were mixed with oneanother at room temperature in an open stirred vessel for 15 minutes.The resulting mixture was admixed with 21.5 parts by weight of Tinuvin®400 and 10.7 parts by weight of Tinuvin® 123 (commercial lightstabilizers from Ciba Specialty Chemicals, Inc.) and 15 parts by weightof Lutensol® AT 50 (ethoxylated alcohol having from 16 to 18 carbonatoms in the alkyl radical and containing on average per molecule 50ethylene oxide groups, from BASF Aktiengesellschaft), after which themixture was stirred at room temperature for 30 minutes. Then 0.86 partby weight of dibutyltin dilaurate and 4.68 parts by weight ofdimethylethanolamine were added. The resulting mixture was stirred atroom temperature for a further two hours.

[0179] Subsequently, 735 parts by weight of deionized water in which1.462 parts by weight of ammonium acetate had been dissolved were addedin small portions to the mixture. After an interval of 15 minutes, afurther 780 parts by weight of deionized water were added at a uniformrate over the course of 30 minutes.

[0180] The resulting aqueous emulsion was diluted with 739 parts byweight of deionized water. After that the same amount of a mixture ofvolatile organic solvents and water was removed from it under reducedpressure on a rotary evaporator, until the solids content was 37% byweight (1 h at 130° C.).

[0181] To set the desired pseudoplasticity, 90 parts by weight ofAcrysol® RM-8W (commercial nonionic associative thickener from Rohm &Haas) and 1.57 parts by weight of Baysilon® AI 3468 (commercial levelingagent from Bayer AG) were stirred into the slurry.

Example 2

[0182] Example 1 was repeated except that the Lutensol® AT 50 was addedto the aqueous phase prior to emulsification.

Example 3

[0183] Example 1 was repeated except that, instead of Lutensol® AT 50,Lutensol® AT 25 (ethoxylated fatty alcohol having from 16 to 18 carbonatoms in the alkyl radical and containing on average per molecule 25ethylene oxide groups, from BASF Aktiengesellschaft) was used.

Example 4

[0184] Example 2 was repeated but using Lutensol® AT 25 instead ofLutensol® AT 50.

Example C1

[0185] Example 3 was repeated except that Lutensol® AT 25 was added tothe finished clearcoat slurry.

Example C2

[0186] Example C1 was repeated but using no wetting agent.

[0187] Table 1 gives an overview of the particle sizes, pseudoplasticityproperties, and filterability of the slurries, before and after passagefive times through a gear pump.

[0188] The results compiled in table 1 underscore the fact that only theinventive slurries had very good filterability and very good gear pumpconveyability. The attenuation in pseudoplasticity brought about by thewetting agents for use in accordance with the invention was acceptable.Moreover, the test results show that the wetting agents are mosteffective if they are added prior to the emulsification in the course ofthe secondary dispersion process. TABLE 1 Particle sizes,pseudoplasticity and filterability of the slurries of the invention(examples 1 to 4) and of the noninventive slurries (examples C1 and C2)Examples: Properties 1 2 3 4 C1 C2 Particle size (μm)^(a)) prior toaddition of thickener: average particle size 6.13 7.16 3.69 2.84 4.266.81 d90 (90% of the particles <) 10.28 13.36 7.76 4.81 9.19 15.12Following addition of thickener: average 6.07 6.89 3.73 2.66 4.32 6.78particle size d90 (90% of the particles <) 10.32 12.22 8.17 5.29 9.715.2 Viscosity^(b)) (dPas) Shear rate (s⁻¹): 10 87 209 224 434 751 904100 45 129 137 244 469 129 1 000 29 79 73 131 229 66 Filterability^(c)):Amount (g) passing through at mesh size: 25 μm 1 943 2 500 2 360 2 410445 0 50 μm — — — — — 336 Filterability^(d)): Amount (g) passing throughat mesh size: 25 μm 1 880 1 200 2 191 450 0 0 50 μm — — — — — —Filterability^(e)): After 5-fold passage through the gear pump: Amount(g) passing through at mesh size 25 μm 107 67 93 300 0 0

[0189] In a first series, the unstressed filtered inventive slurries ofexamples 1 to 4 and the unstressed filtered noninventive slurry ofexample C2 were applied in wedge form to metal test panels and baked at145° C. for 30 minutes.

[0190] In a second series, the stressed filtered inventive slurries ofexamples 1 to 4 and the stressed filtered noninventive slurry of exampleC2 were applied in wedge form to metal test panels and again baked at145° C. for 30 minutes.

[0191] The clearcoats of examples 1 to 4 and of example C2, applied inwedge form, were used to determine the film thicknesses starting fromwhich edge popping marks and flat-area popping marks occurred. Alsodetermined were the film thicknesses starting from which wetting of thesubstrate (cathodic electrocoat, CE, and “black as night” basecoat, BC)occurred. The results can be found in table 2. TABLE 2 Flow propertiesand wetting behavior of the inventive clearcoats 1 to 4 and of thenoninventive clearcoat C2 Examples: Properties 1 2 3 4 C2 Unstressedslurry: From film thickness (μm) Edge popping: 168 145 150 150 160Flat-area popping: 89 79 90 89 76 From film thickness (μm) Wetting ofCE: 24 18 15 15 19 BC: 28 11 11 19 19 Stressed slurry: From filmthickness (μm) Edge popping: 166 150 163 149 not measured Flat-areapopping: 73 86 61 80 not measured From film thickness (μm) Wetting ofCE: 25 18 18 15 not measured BC: 12 15 14 11 not measured

[0192] For a third series, a so-called integrated system was preparedusing a black basecoat material.

[0193] For this purpose, steel panels coated cathodically withcommercially customary electrocoat material were first of all coatedwith a functional coat (Ecoprime®; BASF Coatings AG) using agravity-feed cup gun. After a 5-minute flashoff at room temperature, ablack aqueous basecoat material (Ecostar®; BASF Coatings AG) was appliedto the functional coat in the same way and then dried initially at 80°C. for 5 minutes.

[0194] After the panels have cooled, the stressed filtered inventiveslurries of examples 1 to 4 were applied in the same way. The panelswere then flashed off for 5 minutes and then dried initially at 40° C.for 15 minutes. Thereafter, they were baked in a horizontal position at145° C. for 30 minutes.

[0195] The applied wet films were chosen so that, after baking, the dryfilm thicknesses for the functional coat and for the aqueous basecoatwere each 15 μm.

[0196] Important performance properties of the inventive clearcoats 1 to4 can be found in table 3. TABLE 3 Flow properties (wave scan) andgloss/haze of the inventive clearcoats 1 to 4 Examples Properties 1 2 34 Film thickness (μm) 54 46 52 45 Gloss/haze (20°) to DIN 67530:  83/11 83/12  83/5  83/5 Wave scan^(a)) Longwave/shortwave   3.2/14.1  2.6/14.5   2.7/13.6   3.3/12.9

[0197] The gloss and the flow were very good. The chemical resistance ofthe inventive clearcoats was likewise very good.

What is claimed is:
 1. A pseudoplastic clearcoat slurry comprising solidand/or highly viscous particles which are dimensionally stable understorage and application conditions and at least one wetting agentselected from the group consisting of alkoxylated fatty alcohols havingfrom 16 to 18 carbon atoms in the alkyl radical and containing onaverage per molecule at least 20 oxaalkanediyl groups.
 2. Thepseudoplastic clearcoat slurry as claimed in claim 1, wherein thewetting agent contains on average per molecule at least 25 oxaalkanediylgroups.
 3. The pseudoplastic clearcoat slurry as claimed in claim 2,wherein the wetting agent contains on average per molecule at least 45oxaalkanediyl groups.
 4. The pseudoplastic clearcoat slurry as claimedin any of claims 1 to 3, wherein the oxaalkanediyl groups are selectedfrom the group consisting of 1-oxapropane-1,3-diyl,1-oxabutane-1,4-diyl, 1-oxabutane-1,3-diyl, 1-oxapentane-1,5-diyl, and1-oxapentane-1,3-diyl.
 5. The pseudoplastic clearcoat slurry as claimedin claim 4, wherein the oxaalkanediyl groups are selected from the groupconsisting of 1-oxapropane-1,3-diyl and 1-oxabutane-1,3-diyl.
 6. Thepseudoplastic clearcoat slurry as claimed in claim 5, wherein theoxaalkanediyl group is 1-oxapropane-1,3-diyl (ethylene oxide group). 7.The pseudoplastic clearcoat slurry as claimed in any of claims 1 to 6,comprising the wetting agents in an amount of from 0.01 to 2.5% byweight, based in each case on the clearcoat slurry.
 8. The pseudoplasticclearcoat slurry as claimed in any of claims 1 to 7, comprising at leastone water-soluble salt which can be decomposed without residue orvirtually without residue.
 9. The pseudoplastic clearcoat slurry asclaimed in claim 8, wherein the salt is decomposable under theconditions of the curing of the powder clearcoat films produced from theclearcoat slurry.
 10. The pseudoplastic clearcoat slurry as claimed inclaim 8 or 9, wherein the salt is decomposable thermally and/or withactinic radiation.
 11. The pseudoplastic clearcoat slurry as claimed inclaim 10, wherein the salt is thermally decomposable.
 12. Thepseudoplastic clearcoat slurry as claimed in any of claims 8 to 11,wherein the salt is selected from the group of ammonium salts.
 13. Thepseudoplastic clearcoat slurry as claimed in claim 12, wherein theammonium salt is selected from the group consisting of ammoniumcarbonate, ammonium thiocyanate, ammonium sulfamate, ammonium sulfitemonohydrate, ammonium formate, ammonium acetate, ammonium hydrogenoxalate monohydrate, diammonium oxalate monohydrate and ammoniumcitrate.
 14. The pseudoplastic clearcoat slurry as claimed in claim 13,wherein the ammonium salt is selected from the group consisting ofammonium carbonate and ammonium acetate.
 15. The pseudoplastic clearcoatslurry as claimed in any of claims 1 to 14, wherein the particles havean average size of from 0.8 to 20 μm and a maximum size of 30 μm. 16.The pseudoplastic clearcoat slurry as claimed in any of claims 1 to 15,curable thermally or thermally and with actinic radiation.
 17. Thepseudoplastic clearcoat slurry as claimed in any of claims 1 to 16,wherein the dimensionally stable particles comprise as bindersmethacrylate copolymers containing in copolymerized form, based on agiven methacrylate copolymer, at least 90% by weight of methacrylatecomonomers, including (meth)acrylate comonomers containing potentiallyionic groups.
 18. The pseudoplastic clearcoat slurry as claimed in claim17, wherein the methacrylate copolymers contain in copolymerized form,based on a given methacrylate copolymer, more than 99% by weight ofmethacrylate comonomers, including (meth)acrylate comonomers containingpotentially ionic groups.
 19. The pseudoplastic clearcoat slurry asclaimed in claim 17 or 18, wherein the methacrylate comonomerscontaining potentially ionic groups are selected from the groupconsisting of acrylic acid, beta-carboxyethyl acrylate and methacrylicacid.
 20. The pseudoplastic clearcoat slurry as claimed in any of claims1 to 19, which is substantially or entirely free from organic solvents.21. The pseudoplastic clearcoat slurry as claimed in any of claims 1 to20, preparable by 1) emulsifying an organic solution of constituents ofthe clearcoat slurry in water to give an emulsion of the oil-in-watertype, 2) removing the organic solvent or the organic solvents, and 3)replacing by water some or all of the volume of solvent removed.
 22. Thepseudoplastic clearcoat slurry as claimed in claim 21, wherein thewetting agent is added to the organic solution and/or to the water priorto step 1) of the process.
 23. The use of the clearcoat slurry asclaimed in any of claims 1 to 22 for automotive OEM finishing,automotive refinish, the interior and exterior painting of buildings,the coating of doors, windows and furniture, and industrial coating,including coil coating, container coating, the coating of small parts,the impregnation and/or coating of electrical components, and thecoating of white goods.
 24. The use as claimed in claim 23, wherein theclearcoat slurry is used to produce clearcoats as a part of multicoatcolor and/or effect paint systems.
 25. The use of the pseudoplasticclearcoat slurry as claimed in any of claims 1 to 22 as an adhesive orsealing compound for producing adhesive films and seals.